Hysteretic Mode Converter Digital Frequency Control
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Solution Overview
Problem
Voltage converters introduce unwanted frequency components that can cause noise in electronic devices, particularly in portable communications devices, and existing PWM control methods require complex feedback systems, increasing development and manufacturing costs.
Innovation Solution
A digital control loop for a hysteretic mode voltage converter that includes a timing measure unit and an on-time adjust unit to adjust the switching frequency by counting clock ticks and altering the on-time control signal, allowing precise control of the switching frequency independent of manufacturing processes, device aging, and operating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM control is used to control switching frequency, then switching frequency can be known and set to avoid audible noise, but feedback control system complexity increases
Solution Approach 1:
The patent extracts the frequency control function from the complex PWM feedback system and implements it through a simple frequency counter that counts switching cycles against a reference clock. This separates the frequency measurement function from the power conversion function, achieving precise frequency control without requiring complex feedback control loops.
Solution Approach 2:
The patent replaces the analog PWM feedback control system with a digital counting-based control system. Instead of using analog comparators and feedback loops, the invention uses digital counters to measure and control switching frequency, simplifying the control architecture while maintaining precision.
2Productivity
If switching frequency is increased to improve power conversion efficiency, then conversion efficiency improves, but audible noise and visual artifacts increase
Solution Approach 1:
The patent implements dynamic switching frequency adjustment by allowing the switching frequency to vary within a controlled range while maintaining the digital control framework. The frequency can be adjusted based on operating conditions to optimize efficiency while avoiding problematic frequency ranges that cause audible noise and visual artifacts.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically rather than maintaining a fixed frequency. By using digital control, the frequency can be adjusted in discrete steps to achieve optimal conversion efficiency while avoiding frequency ranges that generate harmful noise and visual effects.
3Device complexity
If fixed switching frequency is used to simplify control, then control system is simpler, but control precision over manufacturing variations and temperature changes is poor
Solution Approach 1:
The patent implements a digital feedback mechanism where the frequency counter continuously monitors the actual switching frequency and compares it against the reference clock. This feedback allows the system to compensate for manufacturing variations and temperature changes while maintaining simple control architecture through digital rather than analog feedback.
4Measurement precision
If PWM control with complex feedback is used, then switching frequency can be precisely controlled, but development and manufacturing costs increase
Solution Approach 1:
The patent uses simple digital counting circuits instead of complex analog feedback components. The frequency control is achieved through basic digital counters and comparators that are inexpensive to manufacture, reducing both development and manufacturing costs while maintaining control precision.
Data Source
AI summary
A system and method for controlling a conversion frequency of a hysteretic mode voltage converter. A digital control loop comprises a timing measure unit having a first input coupled to a reference clock and a second input coupled to a clock based on a switching of the switching of the converter, and an on time adjust unit coupled to the timing measure unit. The timing measure unit counts a number of clock ticks of a clock signal provided by the clock occurring during a period of time specified by a number of clock ticks of a reference clock signal provided by the reference clock. The on time adjust unit adjusts an on time control signal based on the count of the number of clock ticks of the clock signal to alter a frequency of the switching.